Based on a light novel series by Katayama Kentarou, illustrated by Yamamoto Yamato.

16-year-old Shintaro Kurenai is a Mediator - a specialist in settling squabbles between people. Despite his youth and easygoing nature, he is a man of some skills when it comes to protecting both his clients and his client’s interests. And then one day, he is approached by the daughter of a rich and powerful family asking him to be her bodyguard, which somehow ends up with him having a seven-year-old fan, landlord and self-proclaimed fiancé.

Shintaro Kurenai finds himself living in run-down tenement with Murasaki Kuhouin (his new 7-year-old apprentice and landlord) and several other eccentric ladies. His childhood friend (Ginko) acts as his Mediator booking agent. Then there is his (adopted) older sister and martial arts teacher, Yuuno, who does not like to see her Kurenai troubled by any of the difficulties of his Mediator assignments. And Yuuno’s younger (7-year-old) sister, Chi-chan (Houdsuki Chidzuru) also seems to take a troubling worry when her ‘onii-chan’ gets beaten up by Yuuno or his assignments.